be the Riemann (upper case) \(\Xi \) -function, which is an entire function [1]}, [2]}
satisfying functional equation \(\Xi (z)=\Xi (-z)\)  and \(\Xi (\bar{z})=\overline{\Xi (z)}\) . Riemann hypothesis [3]}, [4]} is then equivalent to the statement that all the zeros of \(\Xi (z)\)  are real.
